Improvement in the manufacture of car-springs



N). MIDDLETON & A. M iDDL ETUN, Jr.

Man ufac tu re pf Car-Springs.

N0 135,929. Patented Feb.18,1873.

AM. PHOTO'LII'HUB/PAPH/C 60 NM (DSBOHNES Fiencass;

UNITED STATES- PATENT OFFICE.

NATHAN MIDDLETON AND ALLEN MIDDLETON, JR, OF PHILADELPHIA, PA.

IMPROVEMENT IN THE MANUFACTURE OF CAR-SPRINGS.

Specification forming part of Letters Patent No. 135,929, dated February18, 1873.

10 all whom it may concern.

Be it known that we, NATHAN MIDDLETON and ALLEN MIDDLETON, J r., ofPhiladelphia, Pennsylvania, have invented an Improvement in Oar-Springs,of which the following is a either of iron wire or of tempered steel. Incarsprings having iron-wire spirals as an elastic medium, dependence hasbeen placed upon a large number of such spirals in each spring, the wireof .each spiral being of small diameter, three sixteenths of an inch orthereabout, but in applying these springs'they were generally limited tofreight-cars owing to their restricted elasticity, In making car-springscontaining steel spirals, the practice has been to coil heated rods ofsteel of from one-quarter of an inch to half an inch in diameter, andthen harden and temper the spirals, a process both tedious andexpensive, for,independent of the necessary manipulationwhich itdemands, it is a diflicult matter to impart a uniform degree of temperto the spirals, many of them proving to be defective on bein g properlytested, and others, apparently perfect, beinglikely to break under therepeated shocks and strains to whichthey are subjected when applied torailway cars.

After many experimental tests we have found that a car-spring possessingthe desired permanent elasticity can be made with an elastic mediumconsisting of untempered spirals of cold-drawn or cold-rolled steel, thecold-rolling or cold-drawing-so condensin g the fibers of the metal asto impart a toughness to the same which cannot be acquired by the usualprocess of hardenin g and tempering. The

cold-drawn rod is coiled in a cold state, so

. It is immaterial how many spirals are used in each spring, for thesize of the spirals and their number will depend in a great measurewhether the spring has to be used as a bumper, draw, bolster, or bearingspring; nor is it material how the coils are retained in groups so as toconstitute a self-contained spring.

It may be remarked that in manufacturing the spirals we prefer to makethe coils wide apart in thefirst instance, and afterwards to bring themcloser together by compression.

We prefer to use Bessemer steel owing to its tough nature, but there isother steel of analogous character, which can be cold-drawn orcold-rolled, and can be bent while cold into the desired spirals, whichform a most efficient and economical elastic medium for carsprings.

We claim as our in vention The improvementdescribed in car-springs andin the manufacture thereof-that is to say, a spring composed of a numberof spirals of Bessemer or homogeneous steel wire, colddrawn orcold-rolled, and coiled while cold, as herein set forth.

In'testimony whereof we have signed our namesto this specification inthe presence of two subscribing. witnesses.

NATHAN MIDDLETON.

ALLEN MIDDLETON, JR. Witnesses: WM. A. STEEL, HUBERT HoWsoN.

